Got a BT landline? You can now opt in to its free spam calls filter to escape nuisance callers

Call Protect, offered free to all existing BT landline customers, is expected to divert up to 30 million nuisance calls to home phones every week, according to BT.

The new service is aimed at combatting the large numbers of nuisance calls received in the UK each year, with the telecoms firm recording more than 31 million such calls between 13 and 19 December 2016. The most common form of nuisance call during this period was from accident claims companies, followed by PPI calls and computer-related scams.

For more on how to stop junk mail, calls, texts and emails, see Stop Cold Callers, and for cheap deals on line rental and landline calls, check our Home Phones guide.

How does Call Protect work?

The Call Protect service protects you in three ways:

• It blocks numbers on the BT blacklist.BT proactively scans for the worst-offending nuisance callers nationally – Call Protect will automatically divert calls from such blacklisted numbers to your junk voicemail box. BT says it'll also monitor whether spam callers are frequently changing their numbers in a bid to get round call-blocking services.

• You can create a personal blacklist. In addition to BT's blacklist, you can create your own of up to 100 numbers by adding any number you like – including the last call you received from your home phone. That means future calls from those numbers will also land in your junk voicemail box. What's more, if lots of customers add the same numberto their personal blacklists, BT will add it to its own blacklist, so all Call Protect users benefit.

• You can automatically block certain types of caller. Call Protect also allows you to divert particular types of calls – those from international numbers, withheld numbers and unrecognised numbers.

In all three cases, nuisance calls will be directed straight to a junk voicemail box – completely separate from your regular answerphone – so your phone won't ring at all, and diverted callers will instead be directed to leave a message.

But as with your answerphone, you'll be able to check the junk voicemail box for any messages the callers have left.

How do I get it?

Call Protect is an opt-in service, available for free to all existing and new BT home landline customers – and it's available now.

To activate the service, call 0800 389 1572 from your BT landline or sign up via BT's Call Protect webpage. Once you sign up, it can take up to 24 hours for Call Protect to start working.

How do I blacklist numbers and call types?

You can call 1572 from your landline or log in to the Call Protect portal on BT's website.

You can add specific phone numbers to your personal blacklist, and, as above, divert any calls from international, withheld or unrecognised numbers.

There's also an option to add the last number which called your landline – which means if you've just hung up on a pesky PPI call, you can pick up the phone again and add the caller's number to your blacklist straightaway.

How do I check my junk voicemail box?

You can check for junk voice messages by calling 1572. The box will only store 20 messages at a time, and when it reaches this maximum, each new message you receive will cause the oldest message to be automatically deleted.

Does this replace BT's existing call-barring service?

No – BT says its Choose to Refuse service, which lets you block up to 10 numbers, will continue. If you already use this service you can use it alongside Call Protect if you want – however, you'll need to sign up to Call Protect as it won't be applied automatically.

What other protection is out there?

If you're not a BT customer and so can't get Call Protect, there are still things you can do to protect yourself from nuisance landline calls:

• Call-blocking services: Some landline providers – including Sky and TalkTalk – offer call-blocking services which allow you to bar specific numbers and/or your most recent caller. But these services typically rely on you actively blacklisting nuisance calls, rather than providers proactively screening them out – and there's often a monthly charge for the service.

• Call-blocking phones and devices: In addition to the call-barring services that telecoms firms provide, you can also buy home phones with built-in call-barring capabilities. If you don't want to replace your existing phone, you can buy call-blocking gadgets which connect to it.

  In both cases, they typically allow you to create a list of blocked numbers which can't then call you. However some will instead let you create a 'whitelist' of numbers to allow through, with all other calls screened out.

• Caller ID services: Most providers also offer caller display services which show you the number of the person calling – though this service doesn't prevent your phone ringing in the first place, and as with call-blocking, providers often charge you for the privilege.

• The Telephone Preference Service (TPS):A free service, the TPS is the official central opt-out register on which you can record your preference not to receive unsolicited sales or marketing calls. All organisations are required to respect your preferences unless you've given them specific permission to contact you. Registering online is a quick and simple process.

  Unfortunately some callers may still flout the law by ignoring your wishes, but the TPS website stresses that on the whole it is "very effective" at cutting down on nuisance calls.

• Complaints: If you've received an unwanted call, you can complain to telecoms regulator Ofcom, the police or the Information Commissioner's Office, depending on the precise nature of the call you received. For advice on where to direct your complaint, see Ofcom's guide.

For more help, see our Stop Cold Callers guide.